[sdiy] RE: WP20 VCA

[Scott Gravenhorst]

Is this a contest or a dare or what?  (c:

Grant Richter <grichter at asapnet.net> wrote:
>Hi Ray,
>
>> I just went and did some breadboarding to see what I was thinking 20 years
>> ago. The answer... not much. At best the circuit is very non-linear. In
>> other words if you start with a triangle wave in you get a severely
>> distorted triangle wave out. While experimenting I had to double the gain
>> (200K instead of 100K feedback resistor) so that the signal was a little
>> more above the noise level of the chip. I recommend that you find another
>> VCA circuit. I have a couple of pretty low parts count VCAs on my site but
>> the WP20 stuff was the misguided effort of a much younger and not very
>> electronically savvy man (me). I can't even remember if I had an
>> oscilloscope back then.
>
>Somebody used the term "anti-synth" a while back. That go me thinking about
>a synth deliberately designed from nasty, distorted, non-conforming and
>imperfect modules. (kind of like a PAIA Gnome, only deliberately this time,
>just razzing you John!!!)
>
>So let's call this circuit, part of the "anti-synth" collection. <grin> I
>found a VC waveshaper that sounds like a train wreck (not literally), I will
>post an "anti-synth" design at some point.
>
>Like that CA3096 based VCO with 10K of DeFranco compensation. While still a
>VCO, it has the most waveform shift with frequency. Bad in the traditional
>sense, but a design win for an "anti-synth".
>
>No offense intended here. The brilliant people on this list who are
>dedicated to producing ever improved designs, have my complete admiration.
>But it is kind of fun to reverse your perspective, and see how BAD you can
>design, while still making a module function.
>

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-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
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